JP 2016-022728 A (Reference 1) discloses a fluid pressure pump including a first member (first housing) made of a resin and a second member (second housing) made of a resin. A housing of the fluid pressure pump is formed by joining the first member and the second member to each other by thermal welding. Therefore, a pump chamber is formed in the housing. The fluid pressure pump includes a pump section and an electric motor section. The pump section includes a pump rotor, an impeller provided at an end of the pump rotor, and the pump chamber in which the impeller is accommodated. The electric motor section is provided in order to rotate the pump rotor.
As in Reference 1, in a fluid pressure pump in which a housing is configured by joining the first housing and the second housing to each other by thermal welding and a pump rotor is provided in the housing, a clearance is formed between the pump rotor and a joint portion between the first and second housings in the pump chamber. The clearance between the housing and the pump rotor needs to be as small as possible in the pump chamber of the fluid pressure pump in order to improve a pump performance.
The clearance is formed between the housing and the pump rotor after the first housing and the second housing are joined. That is, because the clearance is formed in the vicinity of the joint portion between the first and second housings, it is necessary to improve dimensional precision related to the first housing, the second housing, and a jig (pressing member), which is used to join the first and second housings to each other, in order to decrease the clearance. The dimensional precision is required in both of the axial direction of the pump rotor and a direction perpendicular to the axis of the pump rotor. For this reason, in the case of the fluid pressure pump having the housing formed by thermal welding, a process of setting an appropriate clearance between the housing and the pump rotor is complicated.
Thus, a need exists for an axial alignment structure for a fluid pressure pump which is not susceptible to the drawback mentioned above.